Been, K & Li, AL 2009, 'Soil Liquefaction and Paste Tailings', in R Jewell, AB Fourie, S Barrera & J Wiertz (eds), Paste 2009: Proceedings of the Twelfth International Seminar on Paste and Thickened Tailings, Australian Centre for Geomechanics, Perth, pp. 281-290, https://doi.org/10.36487/ACG_repo/963_32 (https://papers.acg.uwa.edu.au/p/963_32_Been/) Abstract: Liquefaction of soils is a well documented phenomenon, frequently resulting in catastrophic failures, environmental damage, financial loss and deaths. What seems to be less well appreciated is that liquefaction is simply another constitutive behaviour of soils that can be understood in terms of accepted physics and mechanics. Critical state theory is probably the most widely used mathematical model for the mechanics of soil behaviour since it captures the effect of density (or volume change) on soil behaviour. This paper presents an overview of how the behaviour of tailings (drained, undrained or cyclic resistance) can be quantified within the framework of critical state soil mechanics. It is postulated that paste at the time of deposition is slightly wetter than the critical state, and it is then possible to trace the change of state with the additional of more tailings and consolidation or desiccation. Knowledge of the in situ state allows the material behaviour to be described, and therefore engineering analyses can be carried out.